If images of Christ are a violation of the 2nd commandment then it is certainly sinful to visualize Him in our minds. We know this from His teachings on the Law in Matthew 5. Committing adultery with a woman in our heart would be likened to visualizing Christ in our mind.

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DAVIDIVS DOCTVS VTRIVSQVE LINGVAE
Husband of Emilia
Member: First Reformed Presbyterian Church of Durham (RPCNA) - Durham, NC
Currently in the process of transferring membership to an as-yet-undecided church in Chapel Hill
Student: University of North Carolina at Chapel Hill, German Literature and Classics